3M sell a range of "Command Systems" stick on hooks. These are useful as you can remove them (usually) without damaging the wall. One catch is that the larger hooks come in two parts: a backing plate with the adhesive strip on it and a cover which slides down with the hook on it. If putting up a row of hooks, this can cause a problem (which I just discovered).
According to the instructions you assemble the hook and press it onto the wall. But however carefully you position the row of hooks, if the covers are not firmly in place on each hook, some slip down a bit after being installed and the row looks uneven. Also the hooks have a rounded body making them difficult to position vertically. I discovered, by trial and error, that it was easier to stick just the rectangular backing plates on the wall and only when they are aligned put the covers over them.
As well as the regular hooks, there also metal hooks, cord clips, Velcro type interlocking fasteners, Soap Dishes, and Shower Caddies. The soap dish and shower caddy use a different formulation of adhesive for their Water-Resistant Strips. The catch is these cost much more than regular stick or screw on products. However, being able to move a hook, without having to fill in and repaint over a hole can make it worthwhile. Also the hooks come with spare adhesive strips which can be used to mount other items (I have used to stick a fire alarm to a ceiling, but don't recommend it).